FIG. 2 shows a conventional embodiment of pull-type clutch, in which a diaphragm spring 31 is supported by a clutch cover 2 at its outer peripheral fulcrum point, contacts with a pressure plate 6 at its intermediate fulcrum point, and engages with a release sleeve 33 at its inner peripheral fulcrum point. That is, the diaphragm spring 31 serves to apply an urging load to the pressure plate 6 and also serves as a transmission lever which transmits a release force from the release sleeve 33 to the pressure plate 6 at time of releasing the clutch.
However, when the diaphragm spring is utilized in this way, a structure of the diaphragm spring 31 itself will become a complicated shape having so-called many radial slits. Further, a stroke loss due to deflection of the diaphragm spring 31 is produced to cause a decrease in a transmission efficiency of the release force, so that a release operation performance will become unstable.